The Past, Present and Future of Vaccines

Abstract

When a mother gives birth to a child naturally, in addition to life and love, she gives her baby a third gift which is often ignored: immunity. When the baby passes through the vaginal canal, it comes into contact with a series of “good” bacteria that offer it the first form of adaptation to the surrounding environment. Selected by the adaptive dynamics that are established between the mother and her ecological niche—her relationship with the environment, food, infectious agents and various allergens—they colonize the intestinal tract of the baby, who will inherit a strain of bacteria that are already well adapted to the environment where it will live. Made up of 100 trillion cells with a gene pool that is 100 times greater than the human one, this set of bacteria, known as the intestinal microbiome (the bacterial flora)—today considered like a real organ—has essential functions for human health, such as exploiting the energy of components that are difficult to assimilate, producing useful vitamins, keeping the immune system efficient and above all, competing with pathogenic bacteria and defending us from the aggression of microorganisms. Recent studies have shown that children who are born by caesarean section develop in the first years of life, and often later as well, some complications linked to the malfunctioning of their immune system, not only because they do not have the beneficial maternal “contagion” of useful bacteria but also because they can be damaged by infections due to the pathogenic bacteria present on the skin and in the hospital environment (Dominguez-Bello et al. 2010). In particular, babies born by caesarean section have a greater rate of asthma, allergic reactions, anaphylactic shock (atopic syndromes) and colitic disorders (Gronlund et al. 1999; Salminen et al. 2004; Negele et al. 2004; Debley et al. 2005; Biasucci et al. 2008; Neu and Rushing 2011).